The invention relates to an electrical gas pedal.
In particular, it relates to an electrical gas pedal for automotive vehicles having a desired-value transmitter from which an electric desired-value signal can be fed to an electronic controller unit with speed-of-rotation measurement, with a controlling element which can be controlled by electric signals of the controller unit and can be displaced within a maximum possible desired setting range limited by first and second end positions, by which controlling element, via a transmission unit, a displacement device which is displaceable in an actual-place range which is limited by a first and a second end position can be mechanically actuated to control the engine output, having at least one additional controlling unit for increasing the idling speed of rotation, with a desired-value-transmitter safety contact which closes after a given path of displacement of the desired-value transmitter, and with a controlling-element safety contact which opens after a given adjustment path of the controlling element, and with a safety-contact monitoring circuit which monitors the manner of operation of the safety contacts and, in the event of an error on the part of one of the safety contacts, triggers an error reaction.
In one known system of this type, the safety contacts are so adjusted, in order to permit as early as possible a recognition of errors, that they switch already upon the smallest possible displacement paths. By increasing of the idling speed of rotation as a function of certain factors, such as, for instance, the temperature of the engine at low temperatures, or on basis of the switching on of additional load consumers such as, for instance, an air conditioner, the idling speed control position lies above the switch point of the controlling-element safety contact. When the desired-value transmitter is not actuated and when, therefore, an idling desired-value transmitter signal is present, both safety contacts are unactuated and the safety circuit would respond. In such a case, proper operation of the internal combustion engine would not be possible. This occurs, for instance, in internal combustion engines having injection pumps with separate engine stop. In the case of internal combustion engine having injection pumps with engine stop via an injection pump lever, the position of the controlling element when the engine stop function is not actuated lies in a position above the switch point of the controlling-element safety contact upon an increase in the idling speed of rotation as a result of the above-indicated factors or in the event of a large limiting of the adjustment range. When the desired-value transmitter is not actuated, both switch contacts again are unactuated, i.e. they are disconnected and the safety circuit responds again.
The result hereof is, once again, that, due to the error reaction of the safety circuit operation of the internal combustion engine, in the case of an increase of the idling speed of rotation above the switch point of the controlling-element safety contacts as a result of additional loads or as a function of the temperature of the engine, operation of the internal combustion engine is always impossible when the signal of the desired-value transmitter corresponds to a desired value which lies below the switch contact of the desired-value transmitter safety contact.